Removal of copper and nickel from fatty acids



United States Patent REMOVAL on Conan AND-NICKEL FROM FATTY Acms:

Joseph W. Opie, Minneapolis, Minn., assignor to General Mills, Inc., a corporation of Delaware No Drawing. Application June 20, 1951, Serial No. 232,657

6 Claims. 11. 210- -.41)

Saturated fattyacids: are. frequently prepared'l from:

unsaturated fatty acids by a hydrogenation proceduredn which metallic catalysts (usually nickel in someform) are used. In this procedure and in other processing steps" the fatty acids may also come in contact with metals. such as copper, in valves, transfer lines, pumps, and other;

pieces of equipment.- Copper andnickelLsoaps canthus: be formed and will be contained in the raw undlstilledr acid. For some uses the saturated. acids are first subjected to distillation and asa result'the metals remain behind-in the residue.

copper and nickel, by other means.

before.

to remove the mineral acid. These additional steps are slow and in some instances expensive.

It has now been found possible to remove copper and nickel from saturated fatty'acids without the necessity of resorting to distillation and without thenecessity of cumbersome operations, such as water washing, and the like.

It is therefore an object of the present invention. to provide a novel process of removing copper and nickel from fatty acids by a process which does not requiredistillation of the fatty acids, and which doesnot requirewater washing;

The present invention involves the treatment ofsatu rated fatty acids with bleachingclay in thepresence ofa' strong mineral acid. A wide variety of bleaching clays may be employed. Typical of these are the bleaching clays of the montmorillonite type, such asPikes Peak bleaching clay No. 9077. The bleaching clay is usually employed in a quantity of'from 1% to 3%, preferably about 2%, although larger quantities may beused but are usually found unnecessary. The quantity of strong mineralacid employed may vary from 0. 1% to 1% and preferably about 0.5%. The strong'mineral acidand the bleaching clay may be mixed with, the fatty acidsin any order but must be present simultaneously in. the treatment. Instead of adding the acid andclay separately, it is possible to add the acid to-the clay and then add the acid-containing clay to the fatty acid.

During the treatment no particular temperature is necessary, but the saturated'fatty acids shouldbe-in a liquid condition for intimate contact with the clay and acid. Temperatures of around 185 F. have been found to be satisfactory.

The time of treatment may be varied widely depending upon the results desired. As will be seen from data For some uses for fatty acids, however, the cost of distillation isprohibitive. For-these uses it is necessary to remove traces of metal', particularly "ice Patented June 11, rear given hereinafter, it will be. found that treatment periods of even less than oneminuteare-effective:for: partial re.

, duction in the quantity of copper and nickel. Usually a minimum of about 3 minutes is desirable.

not necessary to extend the treatment period beyond.

It is usually about 20 minutes in order to obtain excellent copper and nickel removal.

A. particular advantage of the present invention is the 4 fact thatthe process resultsin the removal of the-copper and nickel without the. depositof. any residual mineral,

grams of a mixture offattyacids containing approximately 55% palmitic acid and 45% stearic acid were heated to C. and's'tirred. To this was added 0.88 g'. of 85% phosphoric acid and 3 g. of a montmorillonitelbleaching clay (Pikes-Peak- No. 9077). The mixture wasstirred for 20-minutes= and then filtered. The

untreated acids employed as a-st'arting material contained' 312 X- l0 of copper, while the treated product obtained contained 3.7 10 of copper: No freemineral acid was present in thetreated product.

Example 2 Several mixtures of fatty. acids: having approximately.

the samecomposition; as that? described: in Example 1', each of the samples, however, having.diiferent.percent-; ages of copper, were treated according to the process described in Example 1 and were analyzed for copper after treatment The results are indicated in the following table:

Percent Percent Percent Copper Copper Mineral Before After Acid Treatment Treatment 2. 6 10- 1. 7X10- None. 3 10- 2. 0X10: None.

2. 2 10- 1. 5X1O- None.

Example 3 The process previously described was carried out continuously on a pilot plant scale. Fatty acid from storage was continuously fed to a mixing-1 kettle at a rate of 2.76 pounds per minute. An acid activated montmorillonite clay (Super Filtrol F0) was addedat. a rate of 0.0552. pound per minute and phosphoric acid wasfed. at a rate of 0.01623pound 85% H3PO4 per minute. The discharge from the kettle was regulated such-that'the averageresidence time in the kettle'was15 minutes. Themixturewithdrawn was filtered and the fatty acid was fed to a flaking roll. Samples were collected from the outlet, from the filter press and from the flaking rolls at 30 minute intervals. These were mixed into two composite samples which were analyzed for copper. A sample was also taken from the storage kettle and analyzed for copper. The results of these analyses are as follows:

Percent Percent Copper Mineral Acid Sample from storage .2. 9X10 Composite from filter None. Composite from flaker- None.

It is thus apparent that the present process may readily be conducted on a continuous basis.

Example 4 A mixture of fatty acids of approximately the'same composition as those described in Example 1, and having a coppercontent of 2.9 lwas heated to 185 F. It was stirred and treated with 0.5 by weight. of hydrochloric acid (2.3 cc. of 37% acid having a S. G. of 1.18 at 60 F.). 2% by weight of Super Filtrol F0 was added and the mixture was heated and stirred for 15 minutes. It was then filtered and the filtered product was analyzed for copper. It was found to contain 5.9 10- No mineral acid remained in the product.

Example 5 The untreated mixed fatty acids ofthe preceding example were treated with 0.5% by weight of phosphoric acid (0.6% of 85% acid) ,and 2% by weight of Super Filtrol F0 at 185 F. Samples were removed at the end of min, 1 /2 min., 3 min., 5 min., min, and min. The results of the variation in time of treatment are shown in the following table:

Copper content Untreated'material 2.9 10- After minute treatment 2.6 10- After 1 /2 minute treatment 1.8 l0- After 3 minute treatment 3.2)(10- After 5 minute treatment 1.8 10 After 10 minute treatment 1.6 10- After 20 minute treatment 7 x10- It is apparent, therefore, that even on extremely short periods of contact some removal of copper is obtained, and the time required for removal of copper to a very low level is not very extended.

Example 6 The effect of varying concentrations of acid is indicated by the present example in which mixed fatty acids containing aproximately 55% palmitic and 45% stearic acids and having 3.4 10- of copper were treated with 2% of bleaching clay and with 0.1%, 0.25% and 0.5% of phosphoric acid. The results are indicated by the following table:

Copper Material Content,

percent Untreated material 3. 4X1H Untreated material, 2% clay and 0.1% phosphoric acid 2. 8X10 Untreated material, 2% clay and phosphoric acid 7. 9X1O- Untreated material, 2% clay and .5% phosphoric acid 1. 8X10" Example 7 Instead of adding the acid and the clay separately, it is possible to treat the clay with the acid preliminarily and then add the acid-treated clay to the fatty acids. For this purpose a mixture of fatty acids containing 55% palmitic and 45% stearic acids, and having 3X10" of copper, was treated with a bleaching clay upon which 4 had been absorbed 28% by weight of phosphoric acid. A sufficient quantity of this clay was employed to introduce the quantities of phosphoric acid indicated in the following table. The results obtained are indicated in the table:

Percent Percent HaPO4 Used Copper No mineral acid remained in any of these samples. It

5 is evident from this table that the quantity of metals removed does not materially change once a certain minimum quantity of acid has been employed.

I claim as my invention:

1. Process of removing a metal selected from the group consisting of nickel and copper, said metal being present at least partially in the form of soaps, from saturated fatty acids containing the same, which comprises treating the fatty acids in a molten condition with from 0.1, to 1% by weight of a concentrated strong mineral acid in the presence of sufficient bleaching earth to adsorb saidacid and separating the bleaching earth and the adsorbed acid from the fatty acids to leave the saturated fatty acid substantially free from mineral acid.

2. Process of removing a metal selected from the group I consisting of copper and nickel, said metal being present at least partially in the form of soaps, from saturated fatty acids containing the same, which comprises treating the fatty acids in a molten condition with from 0.1 to 1% by weight of a concentrated strong mineral acid in the presence of approximately 2% by weight of a bleaching earth, and separating the bleaching earth and the strong mineral acid adsorbed thereon to leave the fatty acid substantially free from mineral acid.

3. Process according to claim 2 in which the mineral 9 "acid is phosphoric acid.

4. Process according to claim 2 in which the bleaching earth is a montmorillonite clay.

5. Process of removing a metal selected from the group consisting of copper and nickel, said metal being present at least partially in the form of soaps, from saturated fatty acids containing the same, which comprises treating the fatty acids in a liquid condition with approximately 0.5% by weight of concentrated phosphoric acid in the presence of approximately 2% by weight of montmorillonite clay and separating the montmorillonite clay with the phosphoric acid adsorbed thereon from the fatty acids to leave the fatty acid substantially free from phosphoric acid.

6. Process according to claim 2 in which the bleaching earth is an acid activated montmorillonite clay.

References Cited in the file of this patent 

1. PROCESS OF REMOVING A METAL SELECTED FROM THE GROUP CONSISTING OF NICKLE AND COPPER, SAID METAL BEING PRESENT AT LEAST PARTIALLY IN THE FORM OF SOAPS, FROM SATURATED FATTY ACIDS CONTAINING THE SAME, WHICH COMPRISES TREATING THE FATTY ACIDS IN A MOLTEN CONDITION WITH FROM 0.1 TO 1% BY WEIGHT OF A CONCENTRATED STRONG MINERAL ACID IN THE PRESENCE OF SUFFICIENT BLEACHING EARTH TO ADSORB SAID ACID AND SEPARATING THE BLEACHING EARTH AND THE ADSORBED ACID FROM THE FATTY ACIDS TO LEAVE THE SATURATED FATTY ACID SUBSTANTIALLY FREE FROM MINERAL ACID. 